Some SHA256 ASICs (especially S5 and S7, but not all of them) exactly has some issues with DGB, it hangs from time to time or loss blades like 1-of-3 stop hashing. So each pool software works in the differ way and it is possible that it works well at one pool but has problems at another. S4, S4+ and S9 working well with no issues.

The same story with rejected shares, as block time is much less than in Bitcoin, just 15s and sometimes even less, there are more rejected shares. Each share calculated 1-12 seconds depending on Diff and if new block found and new job received from pool before worker found share - it will be stale on the pool and will be paid.And there is also difference in pool engine, some pool has <1.5-2.5% of invalid shares and some >5-7%